The present invention relates to a boat ballast system
Sailing boats typically have a hull, a centreboard depending from the bottom of the hull, a deck or seating, one or more masts with sails attached thereto, means for steering the boat such as a rudder, and lines, pulleys and other apparatus for raising and lowering the sails. Some sailing boats have a cabin or other superstructure. The weight of the combination of the components of the sailing boat determines how much water is displaced by the sailing boat, and consequently the draft of the sailing boat, that is, how deeply within the water the sailing boat floats. A centreboard may be rigidly affixed to and depending from the bottom of the hull of a sailing vessel, or it may be movable and capable of being withdrawn through a well in the hull. U.S. Pat. No. 5,503,097 which issued to Main in 1996 and U.S. Pat. No. 5,036,783 which issued to Ilievsky et al. in 1991 describe examples of movable centreboards that can be withdrawn into a hull of a sailing vessel thereby reducing the draft of the sailing boat while it is being sailed in shallow waters.
When a wind acts on the sails from one or the other side of the sailing boat, the force of the wind on the sails causes the sailing boat to lean to the opposite side. One effect of this leaning is that the sail is no longer substantially vertical and so the propulsive force of the wind on the sails is reduced, and the sailing boat does not move at as great a speed as if the sail received the full force of the wind. A second effect is that a strong wind acting upon the sail can create a turning moment about the longitudinal axis of the sailing boat that is greater than the gravitational force of the weight of the hull of the boat. As a consequence, the sailing boat can be capsized. To counter these effects, ballast can be secured within the bottom of the hull. This has two effects. A desirable effect is that the greater weight of the hull with the ballast increases the gravitational force of the weight of the hull, thus partly overcoming any turning moment arising from the action on the sail of wind from a side of the sailing boat. Consequently, the mast and sail remain in a more upright position, with the results that the sailing boat can travel more rapidly and the chance of the sailing boat capsizing is reduced. An undesirable effect is that the overall weight of the sailing boat is increased, thus increasing the draft and, consequently, the drag of the water on the hull. Therefore use of heavy ballast increases the safety of a sailing boat but reduces the level of performance, in particular, the maximum speed.
What is required is an improved boat ballast system that improves safety of operation of a sailing boat without sacrificing performance of the sailing boat while it is sailed.
According to the present invention there is provided a ballast system for a sailing boat which includes an elongate body having a first end and a second end. Means is provided, at the first end of the elongate body, for suspending the elongate body from a hull of a sailing boat. A ballast weight is positioned at the second end of the elongate body. Means is provided for moving the second end of the elongate body relative to the hull of the sailing boat.
With the ballast system, as described, the ballast weight located at a remote end of the elongate body provides greater stability than an equivalent ballast weight positioned within the hull of the sailing boat. The ballast weight is movable, however, to permit the sailing boat to sail into shallow waters.
Just as there are various configurations of movable centreboards, there are various ways of moving the elongate body to permit the sailing boat to sail into shallow waters. Beneficial results have been obtained when the means for suspending the elongate body is a first pivotal mounting. This enables the elongate body to be pivotally movable between a first limiting position extending from the pivot position toward a stern of the sailing boat substantially parallel with and closely underlying the hull and a second limiting position depending substantially perpendicular to the hull.
As the orientation of the elongate body is altered, it is preferable that the ballast weight be pivotally mounted to the second end of the elongate body by a second pivotal mounting so that the orientation of the elongate body will also be altered. Best results have been obtained when the ballast weight is elongate with a first end, a second end and a top surface. The second pivotal mounting can then be positioned along the top surface at the centre of balance between the first end and the second end such that the ballast weight maintains an orientation substantially parallel to and underlying the longitudinal axis of the sailing boat regardless of the positioning of the elongate body.
The sailing boat must be capable of maintaining stable movement in a variety of depths of water. Regardless of the type of mechanism adopted, it is preferred that the means for moving the second end of the elongate body relative to the hull of the sailing boat be capable of maintaining the elongate body at any selected position between the first limiting position and the second limiting position.
With the ballast system, as described above, the preferred means for moving the second end of the elongate body relative to the hull includes a gear assembly powered by a motor.
According to another aspect of the present invention there is provided a ballast system for a sailing boat which includes the ballast system described above, in combination with a sail boat, as will hereinafter be further described.